LOCAL STRUCTURES OF METALS DISPERSED ON COAL .2. ULTRAFINE FEOOH AS ACTIVE IRON SPECIES FOR STEAM GASIFICATION OF BROWN COAL

The effects of catalyst loading (0.5-10 wt % as Fe) and char conversion on the local structure of iron catalysts during the steam gasification of brown coal have been studied by transmission Mossbauer spectroscopy and extended X-ray absorption fine structure spectroscopy. During the steam gasification, iron species exist as highly dispersed ultrafine particles of FeOOH and as crystalline Fe3O4. The proportion of the former was higher at low char conversion in the low-loading sample and decreased with increase in the amount of iron loading and in char conversion. The ultrafine FeOOH is likely active species for steam gasification of brown coal, since the specific catalytic activity is closely related to the amount of this species.